1、新型光纤材料与器件团队NOVEL OPTIC FIBERS AND DEVICES TEAMMCVD工艺关键技术光纤的四大制造技术?VAD（轴向汽相沉积）?OVD（外部汽相沉积）?MCVD（改进的化学汽相沉积）?PCVD（等离子体化学汽相沉积）MCVD工艺简介工艺简介MCVD工艺步骤1Recipe DevelopmentMain variables for each process steps are following:?Gas flows:bubbler carrier gas,O2,He,Cl2,SF6 etc.?Preform temperature?Carriage speed?So
2、otbox pressure?Ramping of relevant parametersMCVD工艺步骤工艺步骤2Tube preparationTypical MCVD production tube is constructed from three quartz tubes,which are welded together prior to MCVD process.?inlet tube:low quality quartz?substrate tube:high quality synthetic silica,forms final preform?exhaust tube:l
3、ow quality quartz?sleeving tube:synthetic silicaMCVD工艺步骤工艺步骤3Fire Polishing/EtchingPurpose:To clean tube outer and inner surface to improve preform quality.?Temperature:1850-2200C?Reactant flows:O2+fluorine source for etchingSF6+O2MCVD工艺步骤工艺步骤4Cladding and core depositionCladding deposition?Purpose:
4、deposition of protection barrier for core.?Temperature:1900-2100oC?Typical reactant flows:SiCl4,?POCl3,O2,HeCore deposition?Purpose:deposition of refractive?index difference?Temperature:1900-2200oC?Typical reactant flows:SiCl4,?GeCl4,O2,HeMCVD工艺反应机理工艺反应机理SiCl4+O2=SiO2+2Cl2 GeCl4+O2=GeO2+2Cl24POCl3+3
5、O2=2P2O5+6Cl2 4BCl3+3O2=2B2O3+6Cl2热泳效应热泳现象热泳现象是指在温度梯度不为零的气体或悬浮体中，粒子向较冷区域运动的现象。热泳速度正比于温度梯度，而与粒径无关。MCVD工艺步骤工艺步骤5Collapsing?Purpose:to produce glass rod for jacketing and fiber drawing?Typically 2 to 5 forward and 1 backward steps?Temperature:2000-2400oC?Chlorine used as a drying agentMCVD工艺步骤工艺步骤5 Pre
6、form analysis?dimensional and optical parameter evaluation.?important process and quality control toolMore preform analysis?Preform dimensionsPreform,cladding and corediameters from different anglesand longitudinal positions?Refractive indicesSubstrate tube,cladding and corefrom different longitudin
7、al positions?Cutoff,MFD,Chromatic dispersion?Preform non-circularity(preform,cladding,core)?Preform concentricity(preform,cladding,core)MCVD工艺步骤6 Rod in tube sleeving?Purpose:enlarge preform size to improve MCVD productivity?Typical final preform size:40 to 80 mm?Temperature:2000C?Vacuum suction bet
8、ween rod and tube to accelerate joining processFiber drawingMCVD设备系统主要组成设备系统主要组成1.Lathe 2.Gas Control System 3.PC/PLC Control System 4.Gas&Water Supply5.Extract Systems.SGC MCVD MCVD Lathe?Oxy-hydrogen burner?Pyrometer?Flame detectorGas Control and supply System?Silicon Tetrachloride(SiCl4)Supply?Ge
9、rmanium Tetrachloride(GeCl4)Supply?Phosphoryl Chloride(POCl3)Supply?Boron trichloride(BCl3)Supply?Lathe Hydrogen&Oxygen Supply?Sulphur Hexafluoride(SF6)Supply?Chlorine Supply?Oxygen Supply?Helium Supply?Nitrogen Supply?Pneumatics Supply?Drybox temperature controlGas StationExtract Systems1.Gas inlet
10、2.Jet stream column3.Reduction tank4.Neutralization tank5.Absorption column6.Fresh water feed7.Chemical feed8.Waste water discharge9.Pure gas outletGas scrubberJet stream tankOver 90%of silica is collected to the350l jet stream tank.NaOH and Na2S2O3 solutions areautomatically added to the tank tokee
11、p the pH in the tank between 8 and8.5 and Redox potential between-50and+200mV.The washed gas is directed to Neutralization tankthrough a mist eliminator.Jet stream tank receives continuous15-40 l/h overflow from Neutralization tank.Gas scrubber Neutralization tank?The washed gas from stage 1 is?directed to the stage 2 through a setof dampers and mist eliminator(chevron type).?pH of stage 2 tank is kept between10 and 11 to ensure efficient?neutralization of the HCl gas.?HCl+NaOH-NaCl+H2O?Cl2+2NaOH-NaCl+NaClO+H2O新型光纤材料与器件团队NOVEL OPTIC FIBERS AND DEVICES TEAM谢谢！谢谢！
